It’s long been suggested that Sir Alex Ferguson’s retirement would usher in an era of inevitable decline for Manchester United.

Sure enough, just six months after Fergie's retirement, United are well adrift of the Champions League places, have lost successive home matches and look a team disjointed.

With David Moyes’ team off the pace, and seemingly short of confidence and creativity, the questions over the suitability of his handpicked successor grow rather than fade.

Now, using the oracle that is Football Manager 2014, FFT have conducted a highly-scientific experiment to determine who should be the true heir to Sir Alex’s throne, comparing Moyes’ efforts with four other post-Fergie alternatives.

Having simulated the 2013/14 season six times, each featuring a different figurehead at United’s helm, here is what Sports Interactive’s crystal ball unveiled.

Key Results A 4-1 hammering at Manchester City and a 2-0 defeat at Crystal Palace.

League Finish Sixth at the time of his sacking on December 18 2013.

As in reality, Moyes struggled in the summer transfer window with Marouane Fellaini his only recruit. His training methods also saw Robin van Persie side-lined through injury while Javier Hernandez became disillusioned with his role, handing in a transfer request (the little digital Mexican eventually left for Juventus in January).

United started the season well, but this success wasn’t to last and they soon tumbled towards mid-table. On the plus side, United did top their Champions League group, but Moyes’ European exploits weren’t enough to ease the pressure.

You could be forgiven for thinking this all sounded a little familiar, but th simulation suggests things could get worse for Moyes. A defeat at Selhurst Park was the final nail in his virtual coffin, with the Scot replaced by Marcelo Bielsa on December 18. The Argentine was at least able to drag United back up into the top four by the season’s end.

It's probably just as well the real Manchester United aren't heading to Selhurst in the next week...

Key Results Sacked after losing five games in late October and November, following defeats to Cardiff City, Manchester City and Liverpool at home.

League Finish Sixth at the time of his sacking on November 30 2013.

What if, rather than reconciling with Roman Abramovich, Mourinho had taken his unmatched trophy-winning record to Old Trafford?

Well, if our simulation is to be believed, it seems his bravado would soon see him come unstuck, with his antagonisms jarring with the realities of the team’s performances.

The board may have forgiven his war-waging in the press and a touchline ban had he brought results, but key defeats to Liverpool and City in respective home and away derbies soured relations. The Liverpool loss proved to be the final straw with Klopp replacing Mourinho with immediate effect.

The German, having made two January signings, lifted the League Cup against Arsenal but failed to win any other competitions, knocked out by Wigan in the sixth round of the FA Cup and bested by Dortmund in the quarterfinal of the Champions League.

United’s league momentum dwindled, finishing a distant fourth as Marcelo Bielsa masterminded Chelsea to a title-winning points tally of 91 (second placed City finished with 72).

Key Results A slow start and middling form over the festive period gave way to an unbeaten run stretching from February to the end of the season, allowing United to pip Arsenal to third (the Gunners managed by David Moyes, of course...)

How do you replace an institution like Sir Alex Ferguson? Why, by bringing in one of the only managers whose longevity can (almost) match the Scot's: Arsene Wenger.

The Frenchman’s arrival at Old Trafford may have shocked the pretend footballing world, but he struggled to inspire his new team in the opening months of the season, with a raft of new signings taking their time to settle and meld with the club’s existing personnel.

United hovered between fifth and sixth for most of the season, with Wenger pleading for patience as he sought to reshape the club’s backroom set-up and plan for the future by signing the likes of Youri Tielemans and giving games to Adnan Januzaj and Wilfried Zaha.

Despite some promise, the former Arsenal manager was unable to back up his ideas with any silverware, leaving the Old Trafford hierarchy nervous that he would bring the trophy drought of his old team to the once moist Old Trafford.

He secured a third placed finish, but the algorithm-based board weren't entirely satisfied...

Key Results Martinez’s only two losses in a row didn’t come until late April, offering Arsenal a way back into the title race. A nervy season finale was assured by two draws in United’s final games against Aston Villa and West Ham.

With Everton’s strong start to the season in mind, we sent Roberto Martinez to Old Trafford instead of Goodison Park, with Martin O’Neill taking the Toffees job instead of Ireland.

The Spaniard led United to a 21st Premier League title, bagging the League Cup along the way yet there were issues. He was beaten at his own game in the Champions League against Ajax as United crashed out in the second round from an away goal in a 1-1 aggregate draw.

United’s season almost collapsed in the final weeks too, losing two games in a row in April, followed by later defeats to Cardiff and Manchester City. Their last two games were testy draws to Villa and West Ham.

Arsenal finished just a point behind: the champions’ triumph almost turned to disaster.

How about if, having decided they needed to replace Fergie’s wily experience, United turned to QPR’s Harry Redknapp, giving the name who pushed Spurs to an unlikely title tilt one last shot at the big time?

To the surprise of many, he almost succeeded.

Limiting his transfer dealings to the summer for once, Redknapp brought in some surprising names to renovate United’s midfield, eventually finishing second in the league.

He also exorcised his demons by beating Villas-Boas’ Spurs in the FA Cup final.

Unfortunately he struggled elsewhere, knocked out in the third round of the League Cup by West Ham and the second round of the Champions League by Atletico Madrid.

Having cut his managerial teeth in his homeland with Molde, Ole Gunnar Solskjaer proved to be a risk worth taking on his return to Old Trafford, leading United to a Premier League and FA Cup double in his first season back at the club.

Solskjaer secured title No. 21 by winning seven and drawing three of their final 10 games having suffered patchy form in November, December and March. He didn't lose a match to any of United's big rivals.

In Europe he struggled, knocked out by Dortmund in the second round while Fulham triumphed in their League Cup semi-final.

However the club were delighted with Solskjaer’s unexpected double and the potential shown by their new boss.